Silencing means for steel pipe production lines

ABSTRACT

Silencing means for repressing or reducing noise of impact between steel pipes being transferred by means of electromagnets provided between adjacent skid rails such that magnetic circuits are formed by these electromagnets, skid rails and steel pipes being transferred. Magnetic forces set up by the electromagnets acts to cancel the acceleration of steel pipes rolling on the skid rails to reduce the speed of the steel pipes being transferred, thereby reducing the energy of impact between steel pipes for repressing or reducing noise at the time of impact between steel pipes.

Izumidate et a1.

1451 May 13, 1975 1 SILENCING MEANS FOR STEEL PIPE 1,727,163 9/1929Fehringer et a1, .1 188/164 x NE 1,752,162 3/1930 Fehnnger et all188/164 X PRODUCTION LI 5 1,859,764 5/1932 Bougon 1 1 t v 1 1 .1 310/121 Inventors: o Izumidale, Kltakyushu; 1905.218 4/1933 Crago 188/164 xSusumu ltoh, Hitachi, both of Japan 2,006,759 7/1935 Edgar 193/38 X2.786563 3/1957 Stuart 193/41 [731 Asslgme? Japan 3.225.228 12/1965Roshala 1. 310/12 [22] Filed: May 16, 1972 Primary Examiner-Ev0n C.Blunk [2]] Appl' 253756 Ass/slant Exuminer1ames L. Rowland Armmey,Agent, or FirmCraig & Antonelli Foreign Application Priority Data May 171971 Japan 46-33487 57 ABSTRACT Nov. 24, 1971 Japan 11111111 .1 4693615I Japan N 4693616 Silencing means for repressmg or reducing noise ofimpact between steel pipes being transferred by means 521 LS. Cl. I I IV h 193 4i 310/12. Of electromagnets provided between adjacent Skid 318/rails such that magnetic circuits are formed by these 51 1111. c1. 865g11/20 Electromagnets Skid rails and Pipes being [58] Field of Search193/38-41' ferred- Magnetic forces by electromagnels 198/411 310/12.318/135. 188/164 acts to cancel the acceleration of steel pipes rollingon l l l the skid rails to reduce the speed of the steel pipes [56]References Cited being transferred, thereby reducing the energy of im-UNITED STATES PATENTS pact between steel pipes for repressing orreducing 88/ X n01se at the time of impact between steel pipes. 952,4933/1910 Atwood 1 1 t 1 1 1 l 164 1,673,740 6/1928 Eide 193/41 20 Claims,8 Drawing Figures H w z' 1 J 1 4 p F POWER 1 SOURCE L 1 177 L 8 I 1'71F1 1 11 m 11 1 11 rm H S1 1 1 A 9! 1 1 4 a a. m 1 )0 /v Q J n 1 n 1 1 nj J rm 1 rm 1 r1..

l l 1 LLJ L 5 r 1 I EQ I f "ln I J 1 [TI 1 a NLLJ I 1 .1 g 7/0 54 J 4b 9I 1 [T1 17'] T1 5 1 l 15 I r' -"r' -3-' 5 a 5 /0 5 5 PATENIEDHAY 1 319153.882 981 SHEET 2 BF 4 SILENCING MEANS FOR STEEL PIPE PRODUCTION LINESThis invention relates to silencing means for use in steel pipeproduction lines. In steel pipe production lines in steel plants, wherethe eventual products under manufacture and products are transferred byconcon secutive roller conveyor lines, skid stations are provided atpredetermined positions between adjacent roller conveyor lines fortemporarily storing steel pipes for the purpose of inspection. The skidstation consists of a plurality of transversal skid rails which areusually slanted to facilitate the transfer of steel pipes to thefollowing conveyor line. In this skid station, however, great noise isgenerated due to impact among successively coming steel pipes andtemporarily stored steel pipes. The impact between steel pipes createsnoise of very large energy, resounding to far remote places, so that itconstitutes a public problem where steel plants are operated night andday. Recently, in steel plants giving off great noise provision of meansto repress or reduce such noise is mandatory. Heretofore proposedsilencing means use rotary stoppers provided at the feedout end ofslanted skid rails. However, noise still results from impact between thestoppers and steel pipe. Also, since the diameter of steel pipestransferred is not constant but various, a problem for the position ofinstallation of the stoppers projecting to the side of the skid rails onwhich steel pipes rolls are encountered. Further, the stoppers wear asthey are struck by steel pipes, so that they have a limited service lifebut their replacement is not easy. Furthermore, in order to transfersteel pipes to the following conveyor line means is required to releasethe stoppers acting to hold the steel pipes, which complicates theconstruction involved.

The noise mentioned above is generated as a major portion of the kineticenergy of the steel pipe is converted into sound. Mathematically, theimpact energy E (in N.m) is given as where v and m is mass of pipe (inkg), v is velocity of centroid (in m/s), 1 is moment of inertia (in kg.mw is angular velocity of pipe periphery (in rad/s), g is gravitationalacceleration (in m/s dis pipe inner diameter (in m), D is pipe outerdiameter (in m), S is displacement of pipe (in m), and 9 is angle ofinclination of skid rails.

As is apparent from the above equation, the impact energy E isproportional to the square of velocity v. Thus, the noise due to impactmay be repressed or reduced by reducing the velocity of the steel piperolling over the skid rails.

One method to achieve this is to reduce the angle of inclination of theskid rails. However, a certain minimum inclination angle 8 is requiredfor reduction or ef fective utilization of ground space or facilitatingthe transfer of steel pipes to the following conveyor line, so that itis practically difficult to sufficiently reduce noise by merely changingthe inclination angle 9. In addition.

if it is intended to change inclination angle 6 to B l, the level andposition of the following line should be shifted in consistence with thechanged angle 6 l, which means awful change of installation.

Another method to reduce the steel pipe velocity is to bend the skidrails in an intermediate portion thereof so as to slow down the steelpipe in the bent portion. By this method, however, the steel pipe shouldroll over skid rails for an increased distance, which means that thepossibility of causing damage to the steel pipe is increased. Besides,if the steel pipe completely loses its kinetic energy in the vicinity ofthe crown of the bent portion and turns to roll in the oppositedirection due to its own weight, it will be struck by the followingsteel pipe.

As is shown, with the conventional measures it has been difficult tosecurely repress or reduce noise of impact of steel pipes generated inthe skid station.

An object of the invention is to greatly reduce noise resulting fromimpact of transferred steel pipes rolling over skid rails.

Another object of the invention is to provide the possibility of freelycontrolling the speed of transferred steel pipes rolling over skidrails.

A further object of the invention is to provide a silencing means, whichis capable of greatly reducing noise resulting in the transfer oflongitudinally curved steel pipes over skid rails.

In accordance with the invention, electromagnetics are provided in skidrails to set up magnetic forces tending to cancel the acceleration ofsteel pipes rolling over the skid rails to thereby reduce the speed andhence the impact energy of steel pipes for repressing or reducing thenoise of impact of steel pipes.

More particularly, electromagnetic coils provided between adjacent skidrails are energized to create closed magnetic circuits from theelectromagnets through the skid rails and steel pipes, whereby brakingforces are exerted to the steel pipes rolling over the skid rails.

The weight or mass of steel pipes vary with various outer diameters,lengths and other dimensions of the pipes. According to the invention,the extent of excitation of the electromagnets may be adjusted accordingto the weight of the pipe to thereby repress the transfer speed of thepipe for reducing the impact energy and impact noise.

In order for the invention to be fully understood, it will now bedescribed with reference to the accompanying drawing, in which:

FIG. 1 is a schematic layout ofa skid station incorporating anembodiment of the silencing means according to the invention;

FIG. 2 is a side view of the skid station of FIG. I,

FIG. 3 is a fragmentary sectional view taken along line III-Ill in FIG.1;

FIG. 4 is a layout of a skid station incorporating another embodiment ofthe silencing means according to the invention;

FIG. 5 is a side view of a skid station incorporating a furtherembodiment of the silencing means according to the invention;

FIG. 6 is a layout of a skid station incorporating a still furtherembodiment of the silencing means according to the invention;

FIG. 7 is a front elevational view of the skid station of FIG. 6;

FIG. 8 is a side view of a skid station incorporating a yet furtherembodiment of the silencing means according to the invention.

Referring now to FIGS. 1 to 3, which show one embodiment of theinvention, reference numeral 1 designates a steel pipe feed-ii rollerconveyor line installed on a foundation 2. Numeral 3 designates a steeppipe feed-out roller conveyor line also installed on the same foundation2 and extending parallel to the fcedin roller conveyor 1 and at a lowerlevel. Provided between these roller conveyor lines 1 and 3 are aplurality of suitably spaced, transversal parallel skid lines 4a to 40at a certain inclination angle. These rails are supported on top ofsupport legs 5.

Provided at the end of the skid rails adjacent the feed-in rollerconveyor 1 is a steel pipe introducing means 6, which comprises a shaft7 operated from a drive source not shown and a plurality of fetchingnails 8 secured to the shaft. Extending between adjacent one of the skidrails 40 to 4e are a plurality of suitably spaced, longitudinal parallelcore rods 9 of a magnetic material. The core rods 9 are secured bysuitable means such as bolting or welding to the underside of the skidrails in a satisfactory magnetic relation thereto.

Electromagnetic coils 10 are wound on the individual cores 9 andconnected through power supply lead L to a power source P.S., which iscapable of controlling the excitation of coils 10. The electromagneticcoils 10 are energized such that N and S poles are provided atcorresponding positions of alternate cores 9 and skid rails 40 to 4e.

Steel pipes 11 conveyed by the feed-in roller conveyor l are fetched bythe steel pipe introducing means 6 and put on the skid rails 4a to 4e.

When the electromagnetic coils 10 are excited, N and S poles areprovided at corresponding positions of alternate skid rails 4a to 4e,and the magnetic flux extends from these rails into adjacent space. Inthis state, a steel pipe 11 fetched by the steel pipe fetching means 6and brought on the initial position on the skid rails 4a to 46 as shownby broken lines in FIG. 2, starts to roll over the skid rails due to itsinitial momentum and its own weight.

As the steel pipe I] is brought on the skid rails, the afore-mentionedmagnetic flux extending from the skid rails into adjacent space gets tobe substantially confined in closed magnetic loops formed by steel pipe11, skid rails 4a to 4e and cores 9 between adjacent rails, as shown byarrows. These magnetic loops become shortest when the steel pipe 11reaches a position right above the cores 9, and at which time themagnetic reluctance is minimum. Aiso, the steel pipe 11 on the skidrails always experiences magnetic forces of attraction tending to renderthe magnetic loops shorter. In other words. the cores 9 provideelectromagnetic forces of attraction tending to increase the rollingspeed of a steel pipe on their right side while providing forces tendingto slow down a steel pipe on their left side. Thus, the steel pipe onthe skid rails is accelerated at its positions on the right side of theindividual cores while its speed is reduced at its positions on the leftside of the cores. At the position mid way between two adjacent cores,the steel pipe experiences equal forces of attraction from both of theseelectromagnets. And at this point it rolls by virtue of its aquiredspeed and its weight. In the above manner, the rolling speed of thesteel pipe may be extremely reduced compared with the case of absence ofelectromagnets. Thus, it is possi ble to reduce the impact energy E inequation 1 to thereby reduce the impact noise.

According to the invention, it is possible to appropri ately control thetransfer speed of steel pipe 11 rolling over the skid rails irrespectiveof the weight of the steel pipe, which varies with difference in outerdiameter, length and wall thickness of the pipe, by so arranging as tobe able to control the exciting current through the individual coils 10or vary the number of coils 10 that are energized.

The above speed control may result in residual magnetism in the steelpipe 11. If excessive residual magnetism is present, it sometimeshappens that satisfactory welding of product steel pipes cannot beobtained. It has been found that if residual magnetism in the usualsteel pipe is in exess of I00 gaus, imperfect welding of two steel pipeswould result due to such residual magnetism. To avoid thisinconvenience, the products are usually passed through a tie-magnetizingtunnel for tie-magnetization.

According to the invention, it is possible to reduce the residualmagnetism in the steel pipe so as to dispense with the de-magnetizingtreatment.

FIG. 4 shows another embodiment, with which the residual magnetism isreduced. In this embodiment, the skid rails 4a to 4e as mentioned aboveare provided with non-magnetic regions I2 spaced at a predeterminedinterval along the length of the rails. By this means, the skid railsmay be made to assume opposite magnetic polarities on opposite sides ofeach nonmagnetic region 12.

With this construction, the direction of magnetic flux passing throughthe steel pipe 11 is inverted as the pipe passes each row ofelectromagnets consisting of cores 9 and coils 10. Thus, with the lowfrequency alternating magnetic flux the residual magnetism in the steelpipe is reducedv From the aspect of efficiently utilizing the excitingenergy, it is possible to provide limit switches capable of detectingapproaching steel pipes near the individual coils 10 for energizing thecoils successively in the order of the direction of rolling of the steelpipe for a predetermined period. (In this case, it is necessary todetermine the location of the individual switches by taking the risetime of the coil into consideration.)

Also, since maximum permissive exciting current (maximum current withwhich a steel pipe will not come to a standstill on the skid rails) forvarious steel pipes may be experimentally known, it is possible toachieve automatic transfer of steel pipes through com puter controlbased on empirical data.

In accordance with the invention, the impact energy may also beeffectively reduced by substantially reducing the initial speed of thesteel pipe 11 transferred by the steel pipe introducing means 6 onto theskid rails. Accordingly, the effect of reducing the impact noise may bepromoted by incorporating means to reduce the initial speed of the steelpipe.

FIG. 5 shows a further embodiment intended to this end. In thisembodiment, the end of each skid rail 4 on the side of the feed-inroller conveyor 1 is connected to a floating rail 13 supported forflexure. More particularly, each floating rail 13 is pivotally linked atone end through a pin 14 to the associated skid rail 4 and isresiliently supported by a spring 16 on a support leg 16.

In operation, when a steel pipe fetching and throwing means fetches asteel pipe 11 from the roller conveyor .i. l and introduces it to theskid rail side, while imparting an initial momentum to its, eachfloating rail 13 is rotated in the counterclockwise direction about thepin 14, with each spring 16 being compressed by the weight of theintroduced steel pipe. As a result. the -ating rails 13 are orientatedat an angle with respect to the direction of introduction of the steelpipes. so that they act to cancel the initial speed of the steel pipe.With this construction, by appropriately selecting the spring constantsfor the springs 16 it is possible to completely cancel the initialspeed. The steel pipe with the initial speed reduced in the above mannerrolls on the skid rails and is stored thereon similar to the previousembodiments.

While in this embodiment the floating character of the floating rails 13is provided by the springs 16, it may as well be provided by other meanssuch as pneumatic or hydraulic ones.

in the preceding embodiments, the individual skid rails are arrangedwith their top flush with one another, so that the steel pipe will rollin close contact with the individual skid rails to form closed magneticloops. However. if the transferred steel pipe is curved or if the top ofthe individual skid rails are not flush with each other, desiredmagnetic forces may not be obtained due to gaps formed between the steelpipe and the skid rails. in such case. sufficient repression orreduction of impact noise cannot be expected. Further, to ensurerequired magnetic force provision of means to detect the state ofmagnetic loops and extra power consumption are necessary.

According to the invention. it is also possible to ensure good contactbetween steel pipe and skid rails for effectively extertingelectromagnetic forces to the rolling steel pipe for the speed controlthereof.

FIGS. 6 and 7 show another embodiment. which is intended to realizethis, and in which some of the skid rails are floating rails.

Referring to these Figures, numeral 30 designates rail supportsextending upright from a foundation 2. A plurality of skid rails 31 aresupported on top of the rail supports 30. Among the skid rails 31, thosedesignated as 31a are floating rails supported on respective railsupports 30 via associated springs 32. Connecting adjacent skid railsare core rods 33 of a magnetic material, which are connected to theassociated fixed skid rails 31 by means of bolting or welding and to theassociated floating ski'l rails 31a through a resilient conductor. Thecores 33 carry respective coils 34 wound thereon. Means for exciting thecoils 34 and lead lines thereto are not shown.

When a curved steel pipe rolls over the skid rails, the floating rails31a change their level in conformity to the shape of the steel pipepassing on them by the flexing action of the respective springs 32. sothat their contact with the steel pipe is maintained. Thus, the steelpipe can experience effective magnetic forces of magnetic loops formedas the coils 34 are energized to slow down its sp'-ed. so that he impactenergy given in equation 1 :it the time of its impact with alreadystored steel pipe to repress or reduce noise generation.

he steel pipes fed in the skid station may not be of the same curvedshape. Even if they are of the same shape. their orientation when theypass by certain noims of be individual rails may not be the same.

Therefore. if one floating rail 31a is greatly lowered by a steel pipe.the next steel pipe may not roll in contact with that floating rail 31a.Sometimes, one rail may hinder the contact between a steel pipe and anadjacent rail. If many floating rails 31a are out of contact with asteel pipe, the speed of that steel pipe will be increased to reduce itsdistance from the preceding steel pipe. and in an extreme case it willstrike the preceding steel pipe giving rise to noise.

H6. 8 shows an arrangement with which the above disadvantage isovercome. ln this embodiment. each floating rail 31a consists of aplurality of sections a. b. and c (each being at least as long as thedistance between two consecutively transferred steel pipes) so that asteel pipe may be independently supported on these sections.

The possibility of causing damage to the steel pipe as it jumps from onefloating rail section to the next one may well be eliminated by roundingthe feed-in end of each section or more securely by covering the roundedend of each section with a flexible material such as rubber.

While in the preceding embodiment the springs 32 are used to providefloating character to the floating rails, the floating character may aswell be provided in other ways. for instance with pneumatic or hydraulicmeans. Also, the floating character of the rail may be made to beadjustable, so that each rail may serve as both a fixed rail and afloating rail. Further. where complicately curved steel pipes arehandled or where correction of level difference among the individualrails is difficult, all the rails may be constructed as floating rails.By so doing, the level difference in the rails due to wear thereof maybe absorbed, so that the service life may be increased.

What is claimed is:

l. A silencing means for use in steel pipe production line skidstations. said means comprising a plurality of skid rails for rolling aplurality of steel pipes, said rails being spaced from one another andinclined downwardly from a steel pipe feed-in end to a feed-out end, inuse the steel pipes being fed to said steel pipe feed-in end one afteranother, said skid rails being provided with a plurality of non-magneticregions dividing each said skid rail into a plurality of magneticregions. magnetic bodies magnetically coupling corresponding magneticregions of adjacent skid rails. exciting coils for providingpredetermined magnetic flux extending in magnetic circuits each formedby the associated magnetic body, one of said steel pipes, and themagnetic regions of said adjacent skid rails, and means for continuouslyenergizing said exciting coils such that said skid rails assume oppositemagnetic polarities on opposite sides of each of said non-magneticregions.

2. Silencing apparatus for use in elongated cylindrical steel memberproduction line skid stations to reduce the noise occurring due toimpact of a steel member upon another steel member on the skid and uponarrival in the region of a feed-out end of the skid station. theapparatus comprising a plurality of skid rails spaced from one anotherand inclined downwardly with respect to a horizontal plane from a steelmember feed-in end to the feed-out end so as to permit the elongatedsteel members being fed one after another to roll downwardly from thefeed-in end to the feed-out end under the force of gravity. andelectromagnetic force means being continuously energized for controllingthe speed of travel of the elongated steel members over the path betweenthe feed-in end to the feed-out end and for creating a repelling forcebetween adjacent steel members for spacing the steel members from oneanother to reduce the impact energy of the steel members in the regionof the feed-out end and thereby lessen the noise resulting from impact.

3. Silencing apparatus according to claim 2, wherein saidelectromagnetic force means is disposed substantially in a single planeand lies below the top portion of said skid rails upon which the steelmembers roll.

4. Silencing apparatus according to claim 2, wherein saidelectromagnetic force means include at least one magnetic bodymagnetically coupling at least one pair of adjacent ones of said skidrails, and exciting coil means for providing predetermined magnetic fluxextending in a magnetic circuit formed by said magnetic body, one ofsaid steel members and said pair of skid rails,

5. Silencing apparatus according to claim 4, wherein a plurality ofmagnetic bodies are provided between adjacent ones of plural pairs ofsaid skid rails.

6. Silencing apparatus according to claim 4, wherein a plurality ofmagnetic bodies are provided between adjacent ones of all of said skidrails.

7. Silencing apparatus according to claim 4, wherein a plurality ofmagnetic bodies are provided between at least one pair of adjacent onesof said skid rails at a predetermined interval in the longitudinaldirection of said skid rails.

8. Silencing apparatus according to claim 4, wherein said means forenergizing said exciting coil means energize said coil means such thatthe magnetically couplech adjacent skid rails assume opposite magneticpolarities,

9. Silencing apparatus according to claim 4, further comprisingresilient support means for supporting at least one of said skid railsfor flexure in the vertical direction.

l0. Silencing apparatus according to claim 4, wherein said skid railseach consist of a plurality of separate sections, and further comprisingresilient support means for individually supporting each of saidseparate sections of said skid rails for flexure in the verticaldirection.

11. A method for use in elongated cylindrical steel member productionline skid stations to reduce the noise occurring due to impact of thesteel member upon another steel member on the skid and a stop member inthe region of the feed-out end of the skid station, the methodcomprising the steps of arranging a plurality of skid rails so as to bespaced from one another and downwardly inclined from the steel memberfeed-in end to the feed-out end of the skid station, permitting thesteel members to roll downwardly one after another from the feed-in endto the feed-out end under the force of gravity, applying a magneticforce to the rolling steel members to control the speed of travel of thesteel members over the path between the feed-in end to the feed-out endand to create a repelling force between adjacent steel members forspacing the steel members from one another, and lessening the noiseresulting from impact of the steel member upon another steel member anda stop member by reducing the impact energy of the steel member in theregion of the feed-out end,

12. A method according to claim 11, the step of applying a magneticforce includes the steps of arranging at least one magnetic be ly formagnetically coupling at least one pair of adjacent ones of the skidrails, providing exciting coil means to provide a predetermined magneticflux and energizing the exciting coil means to provide the predeterminedmagnetic flux extending in a magnetic circuit formed by the magneticbody, one of said steel members, and the pair of skid rails.

13. A method according to claim 12, including the step of energizing theexciting coil means so that the magnetically coupled skid rails assumeopposite magnetic polarities.

14. A method according to claim ll, including the step of resilientlysupporting at least one of the skid rails for flexure in the verticaldirection.

15. In an elongated cylindrical steel member production line skidstation wherein elongated cylindrical steel members are fed one afteranother to the skid station, the improvement comprising silencingapparatus for reducing noise occurring due to impact of the steelmembers upon arrival in the region of a feed-out end of the skidstation, the apparatus including a plurality of skid rails spaced fromone another and inclined downwardly with respect to a horizontal planefrom a steel member feed-in end to a feed-out end so as to permit theelongated steel members being fed one after another to roll downwardlyfrom the feed-in end to the feed-out end under the force of gravity, thefeed-out end of the skid station being provided with a stop memher, andelectromagnetic force means for controlling the speed of travel of theelongated steel members over the path between the feed-in end to thefeed-out end for reducing the impact energy of the steel members on oneof the stop member and another of said steel members in the region ofthe feed-out end so as to lessen the noise resulting from such impact,said skid rails being provided with a plurality of non-magnetic ,ntgionsalong the length thereof dividing each of said skid rails into aplurality of magnetic regions, said wtromagnetic force means including aplurality ofinagnetic bodies being provided for magnetically couplingcorresponding magnetic regions of adjacent skid rails, and exciting coilmeans providing predetermined magnetic flux extending in a magneticcircuit formed by the associated magnetic body, and one of steelmembers, and the magnetic regions of said skid rails, and means forenergizing said coil means such that said skid rails assume oppo sitemagnetic polarities on opposite sides of each of said non-magneticregions.

16. Silencing apparatus according to claim 15, wherein said energizingmeans continuously energizes said coil means.

17. A silencing means for use in steel pipe production line skidstations, said means comprising:

at least three essentially parallel skid rails for rolling a pluralityof steel pipes, said rails being spaced from one another and inclineddownwardly from a steel pipe feed-in end to a feed-out end, in use fiiesteel pipes being fed to said steel pipe feedin end one after another;

at least one magnetic body arranged at each of the spaces between saidskid rails from said feed-in end to said feed-out end, every adjacenttwo of said skid rails being connected by at least one magnetic body,

electromagnetic coils for individually magnetizing said magnetic bodies;and

9 10 means for continuously energizing said electromagone of the stopmember and another of said pipes in the netic coils so that adjacentSkid rails are magneregion of said feed-out end so as to lessen thenoise retized in opposite polarity to each other when said Sulting f himpact. elecimmagnetic coils are energized whereby a 19. A silencingmeans according to claim 17, wherein magneflc cifcuit i f g 5 aplurality of magnetic bodies are provided between adnetic body, its adacent pair 0 s id rat s an one o jaunt Ones of a Said skid mus smd toretard the travel of smd pipe down the 20. A silencing means accordingto claim 17. wherein incline. A Silencing means according to claimwherein a plurality of magnetic bodies are provided between at saidfeed-out end of said skid station is provided with 1 least l of adjafemones of i i l at a P :1 stop m ber, d th magnetic i i hi h i determinedinterval in the longitudinal direction of said formed serves forcontrolling the speed of travel of said kid rails.

pipes for reducing the impact energy of the pipes on

1. A silencing means for use in steel pipe production line skidstations, said means comprising a plurality of skid rails for rolling aplurality of steel pipes, said rails being spaced from one another andinclined downwardly from a steel pipe feed-in end to a feed-out end, inuse the steel pipes being fed to said steel pipe feed-in end one afteranother, said skid rails being provided with a plurality of non-magneticregions dividing each said skid rail into a plurality of magneticregions, magnetic bodies magnetically coupling corresponding magneticregions of adjacent skid rails, exciting coils for providingpredetermined magnetic flux extending in magnetic circuits each formedby the associated magnetic body, one of said steel pipes, and themagnetic regions of said adjacent skid rails, and means for continuouslyenergizing said exciting coils such that said skid rails assume oppositemagnetic polarities on opposite sides of each of said non-magneticregions.
 2. Silencing apparatus for use in elongated cylindrical steelmember production line skid stations to reduce the noise occurring dueto impact of a steel member upon another steel member on the skid andupon arrival in the region of a feed-out end of the skid station, theapparatus comprising a plurality of skid rails spaced from one anotherand inclined downwardly with respect to a horizontal plane from a steelmember feed-in end to the feed-out end so as to permit the elongatedsteel members being fed one after another to roll downwardly from thefeed-in end to the feed-out end under the force of gravity, andelectromagnetic force means being continuously energized for controllingthe speed of travel of the elongated steel members over the path betweenthe feed-in end to the feed-out end and for creating a repelling forcebetween adjacent steel members for spacing the steel members from oneanother to reduce the impact energy of the steel members in the regionof the feed-out end and thereby lessen the noise resulting from impact.3. Silencing apparatus according to claim 2, wherein saidelectromagnetic force means is disposed substantially in a single planeand lies below the top portion of said skid rails upon which the steelmembers roll.
 4. Silencing apparatus according to claim 2, wherein saidelectromagnetic force means include at least one magnetic bodymagnetically coupling at least one pair of adjacent ones of said skidrails, and exciting coil means for providing predetermined magnetic fluxextending in a magnetic circuit formed by said magnetic body, one ofsaid steel members and said pair of skid rails.
 5. Silencing apparatusaccording to claim 4, wherein a plurality of magnetic bodies areprovided between adjacent ones of plural pairs of said skid rails. 6.Silencing apparatus according to claim 4, wherein a plurality ofmagnetic bodies are provided between adjacent ones of all of said skidrails.
 7. Silencing apparatus according to claim 4, wherein a pluralityof magnetic bodies are provided between at least one pair of adjacentones of said skid rails at a predetermined interval in the longitudinaldirection of said skid rails.
 8. Silencing apparatus according to claim4, wherein said means for energizing said exciting coil means energizesaid coil means such that the magnetically coupled adjacent skid railsassume opposite magnetic polarities.
 9. Silencing apparatus according toclaim 4, further comprising resilient support means for supporting atleast one of said skid rails for flexure in the vertical direction. 10.Silencing apparatus according to claim 4, wherein said skid rails eachconsist of a plurality of separate sections, and further comprisingresilient support means for individually supporting each of saidseparate sections of said skid rails for flexure in the verticaldirection.
 11. A method for use in elongated cylindrical steel memberproduction line skid stations to reduce the noise occurring due toimpact of the steel member upon another steel member on the skid and astop member in the region of the feed-out end of the skid station, themethod comprising the steps of arranging a plurality of skid rails so asto be spaced from one another and downwardly inclined from the steelmember feed-in end to the feed-out end of the skid station, permittingthe steel members to roll downwardly one after another from the feed-inend to the feed-out end under the force of gravity, applying a magneticforce to the rolling steel members to control the speed of travel of thesteel members over the path between the feed-in end to the feed-out endand to create a repelling force between adjacent steel members forspacing the steel members from one another, and lessening the noiseresulting from impact of the steel member upon another steel member anda stop member by reducing the impact energy of the steel member in theregion of the feed-out end.
 12. A method according to claim 11, the stepof applying a magnetic force includes the steps of arranging at leastone magnetic body for magnetically coupling at least one pair ofadjacent ones of the skid rails, providing exciting coil means toprovide a predetermined magnetic flux and energizing the exciting coilmeans to provide the predetermined magnetic flux extending in a magneticcircuit formed by the magnetic body, one of said steel members, and thepair of skid rails.
 13. A method according to claim 12, including thestep of energizing the exciting coil means so that the magneticallycoupled skid rails assume opposite magnetic polarities.
 14. A methodaccording to claim 11, including the step of resiliently supporting atleast one of the skid rails for flexure in the vertical direction. 15.In an elongated cylindrical steel member production line skid stationwherein elongated cylindrical steel members are fed one after another tothe skid station, the improvement comprising silencing apparatus forreducing noise occurring due to impact of the steel members upon arrivalin the region of a feed-out end of the skid station, the apparatusincluding a plurality of skid rails spaced from one another and inclineddownwardly with respect to a horizontal plane from a steel memberfeed-in end to a feed-out end so as to permit the elongated steelmembers being fed one after another to roll downwardly from the feed-inend to the feed-out end under the force of gravity, the feed-out end ofthe skid station being provided with a stop member, and electromagneticforce means for controlling the speed of travel of the elongated steelmembers over the path between the feed-in end to the feed-out end forreducing the impact energy of the steel members on one of the stopmember and another of said steel members in the region of the feed-outend so as to lessen the noise resulting from such impact, said skidrails being provided with a plurality of non-magnetic regions along thelength thereof dividing each of said skid rails into a plurality ofmagnetic regions, said electromagnetic force means including a pluralityof magnetic bodies being provided for magnetically couplingcorresponding magnetic regions of adjacent skid rails, and exciting coilmeans providing predetermined magnetic flux extending in a magneticcircuit formed by the associated magnetic body, and onE of steelmembers, and the magnetic regions of said skid rails, and means forenergizing said coil means such that said skid rails assume oppositemagnetic polarities on opposite sides of each of said non-magneticregions.
 16. Silencing apparatus according to claim 15, wherein saidenergizing means continuously energizes said coil means.
 17. A silencingmeans for use in steel pipe production line skid stations, said meanscomprising: at least three essentially parallel skid rails for rolling aplurality of steel pipes, said rails being spaced from one another andinclined downwardly from a steel pipe feed-in end to a feed-out end, inuse the steel pipes being fed to said steel pipe feed-in end one afteranother; at least one magnetic body arranged at each of the spacesbetween said skid rails from said feed-in end to said feed-out end,every adjacent two of said skid rails being connected by at least onemagnetic body; electromagnetic coils for individually magnetizing saidmagnetic bodies; and means for continuously energizing saidelectromagnetic coils so that adjacent skid rails are magnetized inopposite polarity to each other when said electromagnetic coils areenergized, whereby a magnetic circuit is formed by each respectivemagnetic body, its adjacent pair of skid rails and one of said pipes toretard the travel of said pipe down the incline.
 18. A silencing meansaccording to claim 17, wherein said feed-out end of said skid station isprovided with a stop member, and the magnetic circuit which is formedserves for controlling the speed of travel of said pipes for reducingthe impact energy of the pipes on one of the stop member and another ofsaid pipes in the region of said feed-out end so as to lessen the noiseresulting from such impact.
 19. A silencing means according to claim 17,wherein a plurality of magnetic bodies are provided between adjacentones of all said skid rails.
 20. A silencing means according to claim17, wherein a plurality of magnetic bodies are provided between at leastone pair of adjacent ones of said skid rails at a predetermined intervalin the longitudinal direction of said skid rails.